An amoebic liver abscess can have a variety of clinical presentations. In this chapter, the general well-recognised clinical features of amoebic liver abscess are discussed.

Age
Although an amoebic liver abscess can develop at any age, it is more frequently encountered in adult life with the highest incidence occurring in the third, fourth and fifth decades. The disease is rare at the two extremes of life. The age-wise distribution of this disease noted by various observers is presented in Table I.

Table I

From the above date, it is obvious that 75-90% of the total cases occur between the ages 21 and 50. Below 20 years of age, the incidence is less than 7% and above the age of 50, it is less than 21% . It must, therefore, be noted that no age is exempt and cases have been encountered in infants^4,5 as well as in elderly individuals.

Sex
Amoebic liver abscess is far more common in males than in females. About 85-95% of the total cases seem to occur in males. This higher incidence in males is still unexplained. Since there is a higher incidence of intestinal amoebiasis in males, one would also expect to find a higher incidence of amoebic liver abscess in them. However, even after allowing for this factor, the incidence in females remains much lower! The sex incidence of this disease is shown in Table II.

Table II

Race
Earlier workers¹¹ noticed that the incidence of amoebic liver abscess was lower in the native population of the tropics as compared to that in the resident whites. This, still, has not been substantiated by later workers.

Diarrhoea and dysentery
About 40% patients with liver abscess complain of diarrhoea while only 10% suffer from amoebic dysentery with trophozoites present in the stool. Roughly, 50% give a previous history of dysentery. But there is a wide variation in the reported series.
Craig¹² has enumerated the findings of various authors. He states that 60-90% give a previous history of dysentery or attacks of severe diarrhoea. In our series of 200 cases, in 60% a past history of diarrhoea was elicited whereas only 30% gave a past history of dysentery.
However, hepatic complications have been reported in individuals who have never had dysentery before.¹ If there is a history of an European patient having been to an endemic areas or an American soldier to a tropical region, even as much as 20 to 30 years earlier, the diagnosis of amoebic liver abscess should still be considered.¹³

Alcohol
Ochsner and DeBakey¹⁴ attribute higher incidence in males to alcoholism, which predisposes to hepatitis and trauma. Very few workers have tried to confirm the actual relationship of alcohol to amoebic liver abscess. Alcohol is commonly believed to play some role in the etiology of amoebic liver abscess and many patients give a past history of consuming it. According to some authors the incidence varies from 20%15 - 62.5%^16,17. In our series the incidence was 60%. Klatskin¹⁸, Rajasuriya¹⁹ and Ramachandran¹⁷ have tried to go into more details regarding the amount and the type of alcohol consumed and the duration of the addiction. According to Anderson,²⁰ the consensus of opinion, however, supports the contention that alcoholism predisposes to amoebic abscess.

Other predisposing factors
In my experience, I have seen a dozen patients who have had an attack of typical viral hepatitis just preceding an illness of amoebic liver abscess. I cannot interpret the relationship between the two illnesses.
According to Carig¹², other predisposing factors are exposure, improper diet, mental anxiety and worry. Trauma over the hepatic area may lead to lowered resistance to infection. Unaccustomed physical exertion and sudden violent movements of the chest have been noted to precede the onset of clinical manifestations of amoebic liver abscess.²¹ History of having consumed steroids must be enquired into, since this drug may provoke a fulminating progression of hepatic amoebiasis.²²

Onset of disease
Most authorities agree that the patients may present with acute onset of less than a week’s duration or the illness may have had an insidious onset, spread over several months. Thus, in practice one sees three types of onset - (1) acute, (2) subacute and (3) chronic. In our series of 200 cases, 40% patients presented with an acute onset and 10% with a chronic onset of few months’ duration. The majority (50%) presented with the subacute type of onset of a few weeks’ duration. The findings of other authors are presented in Table III.

TABLE III

From the above table it is apparent that the majority of patients have a subacute onset.
It should be remembered that the duration of the history, however, has little clinical significance and is not reliable indicator of the prognosis.

SYMPTOMS OF AMOEBIC LIVER ABSCESS
Majority of the patients present with pain and fever. Few cases are asymptomatic and are discovered only when complications occur. DeBakey and Jordan²⁴ classified the symptoms as local and systemic.

Table IV demonstrated the frequency of various symptoms in order of frequency are fever with or without chills, rigors or night sweats, weakness, diarrhoea or dysentery, anorexia, nausea or vomiting, etc.

TABLE IV

SYSTEMIC SYMPTOMS

FEVER

The incidence of fever varies from 46-95%. Sometimes, however, fever may be entirely absent. The fever may be continuous or intermittent and may be accompanied by rigors.^23,30 According to Wilmot²⁵ rigors are distinctly uncommon. In our experience chills are frequent in the beginning of the illness only. In amoebic liver abscess of acute onset, the temperature is often high and of a remittent variety accompanied by profuse perspiration. In the chronic forms the fever is often low, develops more gradually and may be the only symptom for weeks. In such cases sweating is less pronounced and chills may not occur.
Acute cases with high fever and right basal pulmonary signs may be wrongly diagnosed as right basal pneumonia. Cases in which the fever lasts for several weeks may often be misdiagnosed as enteric fever or tuberculosis. Madangopalan²⁹ found that 0.7% cases of P.U.O. had amoebic liver abscess.

OTHER SYSTEMIC SYMPTOMS
Weakness may appear early in amoebic liver abscess but is very prominent in advanced cases. A feeling of lassitude and fatigue may be present in subacute and chronic forms of the disease. Other symptoms like weight loss are always present, particularly if the duration of illness is more than two weeks.⁹ Where the illness extends over several months, the weight loss may exceed one-third of the lean body-mass so that these cases are often misdiagnosed as carcinoma of the liver.²⁹ Weight loss is found to occur in 10-50% of the patients in various series.
Cough is another common symptom. It is usually dry and unproductive. Amoebic liver abscess with basal pulmonary signs may also given rise to breathlessness.²⁰ Sometimes patients suffer from hiccough.
Other symptoms which may occur in a small number of patients are anorexia, nausea, vomiting and oedema feet. Sometimes the latter is associated with a distended abdomen due to ascites.
Mild jaundice may be present in a few patients. Deep jaundice of the obstructive type may rarely be the presenting symptom.²³

LOCAL SYMPTOMS
PAIN
The earliest and most common local symptom of amoebic liver abscess is pain. It is present in 65% to almost 100% cases (Table IV).
Character of pain. In uncomplicated amoebic liver abscess it may start as a dull ache or a feeling of heaviness and become sharp and stabbing later on. Pain may increase by change in position, deep breathing or coughing. Alcohol is also known to aggravate it.³⁰ The pain may become worse at night. Inactivity and turning to the opposite side relieves the pain. The latter is probably due to the release of tension on the liver capsule by opening up of the intercostal spaces.
Site and radiation of pain. The most common site of pain is the right hypochondrium and the right lower chest anteriorly.
Localisation of the pain will depend upon which surface and the lobe of the liver is the abscess located. Right lobe abscess will produce pain the right lower chest anteriorly or posteriorly. Pain may be felt in right hypochondrium, right subcostal area or in the area of the gall bladder.
A patient having an abscess beneath the right dome of the diaphragm will complain of pain over the tip of the right shoulder.²⁵ Sometimes, there is only a soreness of the right shoulder. Occasionally pain may be referred to the right side of the neck. A right lobe abscess may also present with pain in the right flank, right loin or in the right scapular region in the back. In amoebic liver abscess complicated by pleuropulmonary syndrome, pain may be felt over part or whole of the right hemithorax.
In amoebic abscess of the left lobe, pain is felt in the epigastrium and left hypochondrium. It may radiate to the left back, the left loin and the scapular region. A rupture of the left lobe abscess into left hemithorax may produce pain the left hemithorax. When it ruptures into the pericardial sac, pain may be precordial or restrosternal in location. Rupture into the peritoneal cavity may result in severe generalised pain of ‘an acute abdomen’. Less commonly, a liver abscess may leak into the peritoneal cavity along the right paracolic gutter and form walled-off abscesses, which may give rise to localised pain in the right illiac fossa. Rarely, chronic peritonitis with adhesions and loculated collection of pus may cause vague upper abdominal pain. Amoebic abscess occurring in patients with dextro-cardia with transposition of viscera will cause pain in the opposite hemithorax. Two such case reports have been published till now.^33,34

SIGNS of AMOEBIC LIVER ABSCESS
Local signs

Hepatomegaly
The most important physical sign in amoebic liver abscess is a tender, enlarged liver. Its incidence in various clinical series is presented in Table V.

TABLE V

The enlargement varies with the site and size of the abscess. With large abscesses the liver may extend into the umbilicus. There may be (i) generalised enlargement of the liver, (ii) enlargement of the right lobe only, (iii) enlargement of the left lobe only, (iv) only upward enlargement of the right or left lobe (this is diagnosed by percussing the upper border of the liver: Quite often in patients with this type of enlargement, an auscultation there is diminished air entry at the right base), (v) enlargement in the horizontal plane towards the left hypochondrium (usually in a left lobe amoebic liver abscess), (vi) posterior enlargement, or (vii) rarely no enlargement at all.
The edge is usually ill-defined, rounded and soft. Often the edge is difficult to feel because of localised rigidity and guarding in the right hypochondrium. Rarely compensatory hypertrophy of the liver in the area around a large abscess cavity may lead to a certain amount of irregularity and even nodularity making differentiation from malignancy of the liver difficult.
Local liver enlargement in the form of a mass or a lump may sometimes be seen in the right hypochondrium or epigastrium. Its surface can be smooth or irregular and its margins may be continuous with the enlarged liver surface. It may be firm to begin with, but later may become fluctuant. Often there is a bulge in the right infra-axillary region.

Tenderness
Tenderness may be diffuse or localised. However, both may occur together, one being superimposed on the other.
Diffuse tenderness is elicited by striking a gentle blow to the right lower chest with the palmar surface of the clenched fist (Fig.1). The whole right lower chest, starting anteriorly and moving posteriorly should be struck, by this ‘Punch’ test. If the liver is palpable, subcostal tenderness should be looked for by pressing that area with the palmar surface of the fingers before and after deep inspiration. Diffuse liver tenderness can also be elicited by the ‘compression sign’ - that is tenderness on antero-posterior compression of the lower part of the chest on the right side¹² (Fig.2)
A localised area of maximum tenderness must be looked for. This area may lie subcostally; if not, it is often found by thumb pressure in the intercostal space (Fig.3). This ‘intercostal tenderness’ is one of the cardinal signs of liver abscess.
Much more informative is the ‘point tenderness’, which is noted more often than generalised ‘intercostal tenderness’. Point tenderness (Fig. 4) is elicited by palpating with the tips of the fingers all over the hepatic area including the right lower chest (anterior and posterior and subcostal area. As against intercostal tenderness which could be present in pleurisy etc., point tenderness is more diagnostic of liver abscess and is also a useful guide as to the side for abscess puncture. Point tenderness and intercostal tenderness are often elicited even in the absence of diffuse liver tenderness. The former is often elicited in the postero-lateral area of a lower right intercostal space (Fig. 4).
Lamont and Pooler²¹ graded the tenderness into the following categories :

1. Grade 0-I : Patients who have no tenderness or who have to be questioned specifically about it.
2. Grade I : Moderate tenderness due to which the patient winces in response to gentle palpation or percussion.
3. Grade II : Severe tenderness due to which the patient moves away from the examining hand.
4. Grade III : Very severe tenderness due to which the patient refrains from the examining hand even before it reaches the affected area.

In their series of 250 cases most patients (45.2%) had Grade II tenderness. 10.4% had Grade 0-I , 37.2% Grade I, while 7.2% had Grade III tenderness.
Another important localising sign is the presence of oedema overlying the ribs, costal margin and anterior abdominal wall. Most often because of a raised right dome of the diaphragm, there is an impaired percussion note, diminished air entry and occasional crepitations at the right base.
A hepatic rub may be elicited in some cases. However, it is a rare finding. In those cases where air has been instilled after tapping, hepatic succussion splash could be elicited.
Rarely, in some patients there may neither be hepatomegaly nor tenderness.³⁵

General signs
The general signs are less important in the diagnosis of amoebic liver abscess (except fever which has already been discussed). On general examination, apart from pyrexia and sweating, a muddy look has been described. It is difficult to appreciate this in Indian patients, though when present, these patients are markedly wasted and the onset of their illness is usually chronic.
Icterus may be detected in a few cases if one looks for it specifically and in good natural light. Rarely swelling of the feet, mild ascites, clubbing of the nails, or signs of hepatic coma may be present.
In many patients the colon when palpated is tender. This tenderness is maximum over the caecum. I have often seen a tender hepatic flexure, being confused with hepatic tenderness. Patients having concurrent dysentery, or who had it in the recent past will have a diffuse colonic tenderness.

Criteria for diagnosis
Since the days of Roger, the diagnosis of hepatic amoebiasis was made with confidence, at the bedside, in a patient with a history of dysentery and the presence of a painful tender hepatomegaly. In 1958, Lamont and Pooler²¹ proposed five diagnostic criteria for hepatic amoebiasis.

1. Tender, enlarged liver
2. Suggestive haematological findings
3. Suggestive radiological findings
4. Demonstration of characteristic ‘pus’
5. Successful antiamoebic drug therapy

In 1978, Quaderi et al³⁶ enlarged upon these and divided them into major and minor criteria for the diagnosis of amoebic liver abscess. The major criteria are the ones suggested by the WHO.³⁷ These include :

1. Enlarged tender liver
2. Radiological evidence of raised dome of the diaphragm
3. Fever and polymorphonuclear leucocytosis
4. A cold area on liver scanning (which is to be done prior to aspiration)
5. Aspiration of amoebic pus from the liver abscess

The minor criteria include :

1. Residence in an endemic area
2. Presence of fever
3. A muddy complexion
4. Fullness of right lower intercostal spaces
5. Polymorphonuclear leucocytosis
6. Demonstration of E. Histolytica from pathology specimen
7. Presence of amoebic ulcers of large bowel on sigmoidoscopy

Of all these criteria mentioned above, aspiration of sterile pus from the liver constitutes the absolute proof of an amoebic liver abscess. To this we should now add demonstration of E. Histolytica in the pus and a positive serological test for amoebiasis.
Once amoebic liver abscess is suspected, therapeutic trial with chloroquine or metronidazole should be started while proceeding to confirm the diagnosis by various investigations available.

Localisation of an abscess is always the second step once the diagnosis of an amoebic liver abscess has been made. Although in centres where a liver scan is available, the clue might be obtained easily, still efforts must be made to localise it at the bed side. The following chapters deal with this problem

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